Process of recovering oil from oil sands



Patented Sept. 8, 1931 UNITED STATES GEORGE W. COGQESHALL, OFWASHINGTON, DISTRICT OF COLUMBIA PROCESS OF RECOVERING OIL FROM OILSANDS No Drawing. Beiiled for abandoned application Serial No. 53,442,flied August 29, 1925. This application tiled January 21, 1931. SerialNo. 510,331.

This invention relates to the recovery of hydrocarbon oils from oilsands, es eciall such as are depleted in the sense that t e rea ilyavailable oil has been removed by the usual pumping methods. It has beenvariously estimated that such depleted sands still retain more thanfifty percent, and up to eighty or even ninety percent of the originaloil and many methods have been proposed in the past for the recovery ofa part of this residual oil. Among such methods which have been tried ona considerable scale and with some measure of success are the use of airunder pressure to cause a movement of the oil from adjacent areas to theoperating Well or wells; and the use of water, sometimes with mineralsalt or alkaline additions, for the same purpose. Both of these methodshave proven effective, in some fields at least, to recover someadditional oil; but in no case, so far as I am aware, has the additionaloil so recovered constituted more than a very small proportion of thatestimated to remain in the sands.

According to the present invention I am able to make relatively highrecoveries of the oil in a sand either before or after the abovementioned treatments, in an economical manner.

My invention contem lates broadly the use for displacing the oi towardthe points of tinal recovery, that is to sa theo crating well or wells,of certain liqui s whic are of the colloid-sue ension orcolloid-solution type, and are c aracterized by their ability to (11slace oil quickly from the ain surfaces; y such surface tension relationsto the so displaced oil that the latter tends to move ahead of theadvancing liquid rather than to mingle with it; and by freedom from anysubstantial tendency to form stable emulsions with the oil. My preferredliquids are moreover both chemically and physically stable under theconditions of use: that is to say, they do not undergo chemical changeby reaction with the constituents of the sands; and

the colloidally suspended or dissolved com-- onents are not removed, toany great extent, at least, by the filtering effect of the bed. Toensure this physical stability I have found it necessary that thecolloid suspensions (or colloid solutions, as they are sometimes termed)should be of a highly dispersed type. It should be understood, however,that my invention is not restricted to the use of colloidal suspensionscontaining particles within any particular dimension limits, sinceconsiderable variation is permissible according to the nature of theparticular sand, or other gangue material as mentioned below, its grainsize, the closeness of packing, etc. An example of a liquid which isneither physically nor chemically stable is an ordinary soap solutionwhich tends to lose its soap content by filtration, on the one hand,and'to clog the sand bed by chemical reactions yielding insolublemetallic soaps, on the other hand. Such ordinary soap solutions aremoreover without substantial effect on the interfacial tension betweenthe oil and the displacing liquid.

Among the materials which are suitable for use in my invention arecolloidal suspensions of sulfonated organic substances which will notform insoluble substances in contact with soluble lime and magnesiumsalts. Such, for example, are certain sulfonated ve etable and animaloils and some of their sa ts, as well as a number of sulfonatedhydrocarbons, both aliphatic and aromatic; also mixtures of thesematerials. Certain of the products obtained by sulfonating animal orvegetable oils in the presence of hydrocarbons also give excellentresults.

A preferred material for in purpose is obtained from the acid sludgefrom the sulfuric acid treatment of petroleum or coal tar products,which is desirable not only by reason of its effectiveness for thepurposes of this invention, but because of its low cost and readyavailability. All of the above may, in general, be employed in acid,neutral or alkaline suspension, and in the form of their :11- kali oralkali earth salts, and in admixture with other materials.

The essential characteristics of the sub stances which I contemplateusing in my in vention are that they are highly dispersed colloidalsubstances and that they do not form a precipitate in the presence oflime and magnesium salts. The suitability of a given colloidal materialfor use in my process of recovering oil from oil sands may readily bedetermined, as far as the latter of the above characteristics isconcerned, by means of the followin sim le test:

. The materia to e used is dissolved in water, preferabl the water whichwill be used in making t esolutions in the field, that is, the surfacewater of the region. This solution is then mixed with an equal volume ofoil well water, that is, water which has been in contact with the oilsands of the field for some time. The mixture is allowed to stand atroom temperature for several weeks.

When common soap or ordinary Turkey red oil or similar materials inone-half of one percent solution is subjected to the above test, aprecipitate is soon formed. This precipitate may be granular, flocculcntor gummy, and may precipitate instantly or only on standing for a numberof days, but the a pearance of any precipitate is an indication that thematerial is unsuitable for the purposes of the invention.

On the other hand a sulfonated hydrocarbon may be obtained from acid sluge, as I have described above, which will not give any precipitate inthis test. While any other method of determining whether a givenmaterial will form an insoluble substance in the presence of lime andmagnesium salts may e used, it will be noted that the test outlinedabove affords a simple and direct method of testing the ropose materialsunder conditions resem ling those under which they are to be used.

As between acid, neutralor alkalinesuspensions, in present preference isin favor of ve slig t alkalinit especially for use with suc i sands asare c osely packed or contain small amounts oi calcium or magnesiumcompounds. Such sli htly alkaline suspensions show a bi h sta ility,both hysical and chemical; t eir physical stability being attributableto their somewhat higher dispersion, and their chemical stability totheir nonreactivity. Acid suspensions undergo neutralization andeventually may become alkaline in passing through these sands, whilemore strongly alkaline suspensions tend to lose alkalinity, possibly byadsorption.

M invention is not limited by theoretical considerations, which are, ofcourse, diflicult or impossible of roof by reason of the inaccessibilityof the ds, except in the form of drill cores. The following explanatoryconsiderations are therefore 0 ered as clarifying the invention withoutlimitation of its scope.

A. depleted sand bed ma be re rded as comprising a more 'or less cose-pac ed sand, the grain surfaces of which are covered b adherent oilfilms, and the interstitial cavities filled with gas. Pumping may removea part of the s, but is ineflective to cause any substantia movement!the oil films.

Air does not operate to lift or displace the oil films, but may causesome movement of oil by dissolving therein under pressure and causingfrothin" when the pressure is released. Water likewise fails to displacethe adherent films, at least to any great extent, since its surfacetension, as compared with oil, is such that the latter wets or adheresto the grain surfaces more strongly than does water; and the same istrue of weak acid or alkaline solutions, such for example as solutionsof sodium carbonate, silicate, borate or the like. Such additional oilrecoveries as are obtainable with water or aqueous alkaline solutionsare attributable in the main to the displacement of some remaininginterstitial 011 as distinguished from the adsorbed or film oil. Asdistinguished from these, my highly dispersed colloid suspensionspossess the property of quickly displacing or lifting the lm oil, owingto their superior wetting power for the sand grains; moreover thesesuspensions tend strongly, as compared with water or aqueous solutions,to drive the oil ahead of the moving body of aqueous liquid, instead ofslipping past the oil particles and commingling with them, with theresult that the ratio of oil to aqueous liquid in the recovered productis decidedly higher in the case of the colloidal sus ensions.Furthermore, as already stated, t e colloidal suspensions exhibit notendency to the formation of emulsions; as a matter of fact, thesesuspensions are effective to break down existing waterin-oil emulsions,even those of a highly stable and refractory t pe.

I do not limit mysel to any particular proportion or range ofproportions of colloid to water in my suspensions, since of course suchconcentration will be chosen as is most economical in any particularfield, having regard to the cost of materials and the recovcriesobtained. Proportions of sulfonated hydrocarbon as low as 02% show someeiicct, and proportions as high as 1.00% or 2% may be used. My usualpractice has been to em- Eltgr about 0.10 to 0.50% of the sulfonatcd oy, but as stated my invention is not restricted to this range.

I believe myself to be the first to employ highly dispersed colloidswhich are both physically and chemically stable in presence of oil sandsfor the purpose of aiding the recovery of oil from oil sands, theexpression highly dispersed being employed in a genera and broad senseto indicate that the deg'ree of dispersion of the colloid particles issuliiciently high so that serious or material losses are not encounteredthrough the filtering effect of the particular oil sand in connectionwith which they are used.

The term sulfonate is used broadly to include such sulfonated oils orhydrocarbons as are above mentioned, or their salts or mixtures thereof,whether in acid, neutral or alkaline solution.

The term oil sands is used herein in its broad sense to include suchother bitumengangue materials as are mentioned above.

This application is a continuation-inart of my application Serial No.53,442, led August 29, 1925.

I claim:

1. Process of recovering oil from oil sands in situ which com risesflowing therethrough an aqueous liqui comprisin 9. hi hly dispersedcolloid materal whic is p ysically anddchemically stable in the presenceof said san s.

2. Process of recovering oil from oil sands in situ which com risesflowing therethrough an aqueous liqui comprisin a highly d1spersedcolloid material mclu mg a sul onate which is physically and chemicallystable in the presence of said sands.

3. Process of recovering oil from oil sands in situ which com risesflowing therethrough an aqueous liqui comprising a highly dlS- persedcolloid material including a hydrocarbon sulfonate which is physicallyand chemically stable in the presence of said sands.

4. Process of recovering oil from oil sands in situ which com risesflowing therethrough an aqueous liqui comprising a highly dispersedcolloid materal which will not form a precipitate when mixed with waterthat has been in contact with said sands.

5. Process of recovering oil from oil sands in situ which com risesflowing therethrough an aqueous liqui comprising a highly dispersedcolloid material mclu ing a sul onate which will not form a precipitatewhen mixed with water that has been in contact with said sands.

6. Process of recovering oil from oil sands in situ which com risesflowing therethrough an aqueous liqui comprising a highly dis- Eersedcolloid materal including a hydrocaron sulfonate which will not form arecipitate when mixed with water that has een in contact with saidsands.

In testimon whereof, I afiix my si ature.

GE RGE W. COGGES ALL.

